This disclosure relates to electronically commutated motors (ECMs), and more particularly, to methods and approaches used for providing a resilient rotor assembly for such motors, which are sometimes referred to as brushless motors. Brushless motors include brushless AC motors and brushless DC motors.
Brushless motors are used in a wide variety of systems operating in a wide variety of industries. As such, the brushless motors are subject to many operating conditions. In such a brushless motor, a permanent magnet rotor and the produced torque may combine to result in cogging, as well as commutation torque pulses. The cogging and the torque pulses may get transmitted to the shaft of the motor, and then onto a fan or blower assembly that is attached to the shaft. In such applications these torque pulses and the effects of cogging may result in acoustical noise that can be objectionable to an end user of the motor.
To counter such operating conditions, introduction of a resiliency between the component that is producing these torque pulses and the shaft that transmits the torque to the fan or blower, which is attached to the shaft, would be desirable. However, the resilient rotor constructions that have been designed and produced are related to such motors where the permanent magnet structure is such that magnets are mounted on the surface of the rotor. In such systems, the resilient components are attached to a central core by metal rods or clips, spot welding, or by tig welding. However, in an interior permanent magnet rotor design, where magnets are interior to the rotor and a laminated structure is used for rotor core, it is difficult to attach a resilient component to rotor core by tig welding or spot welding without increasing a length of the rotor.